


Children In The Tower

by Jake_Matthews



Series: Avengers One Shots [7]
Category: Agents of S.H.I.E.L.D. (TV), Marvel Cinematic Universe, The Avengers (Marvel Movies)
Genre: Age Regression/De-Aging, Bucky Barnes Recovering, Bucky Barnes Remembers, Bucky Barnes is Worthy, Fluff, Gen, tony is an adorable baby
Language: English
Status: Completed
Published: 2015-05-31
Updated: 2015-05-31
Packaged: 2018-04-25 15:27:40
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 9,680
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4966255
Author URL: https://archiveofourown.org/users/Jake_Matthews/pseuds/Jake_Matthews
Summary: <blockquote class="userstuff">
              <p>When an exploding experiment reverts all the Avengers to various stages of childhood, Shield's finest are called in to babysit and try to fix the issue. Cue adorableness.</p>
            </blockquote>





	Children In The Tower

Steve rolled over, coughing. He squinted through the dust left by the explosion, and tried to make sense of what had happened. He stared down at his hands, and he could tell something was wrong, but couldn't quite figure out what. He rolled his shoulders, and frowned. Something definitely felt wrong there. He pushed himself back onto his knees and looked down at his uniform. Normally snug, perfectly fitted to his body, it now hung loose, slack across his chest. He got to his feet, still staring down at his body. He was smaller, but still larger than he had been before Erskine's serum.

"What the hell-?" Steve grabbed his throat, shocked by the hoarse, squeaky noise he'd just produced. He cleared his throat, and glanced down at his body again. "Okay... So I look and sound like a teenager. Gre- *a-hmm* Great." He looked around. The dust had settled mostly, but there seemed to be a lot of rubble around. He put a hand to his ear to activate the comms as he bent to retrieve his shield. "Nat? Tony? Anyone?" Static. Comms were down then. Steve squinted around some more. He knew Sam had been close by, and he'd seen a glimpse of someone in the next room. The interior of this floor was so destroyed it was hard to determine where the next room was, but he struck out in the direction he thought it had been.

"Hello? Anyone there?" He saw a shape shifting under a piece of rubble and rushed forward to help. He pulled the rubble away clumsily, unsure of his strength. This teenage body was the wrong size, the wrong shape, and had less strength than his post-serum body, but still much more than he'd been used to pre-serum. The person under the rubble pushed themselves up, and Steve frowned. Something looked very strange about this person. Their left arm seemed out of proportion, and their clothes, like Steve's, were comically loose on them. Then the long hair was flipped back out of their face, and Steve realised why they looked so strange. "...Bucky?"

Bucky squinted up at Steve. "...Steve? What- *cough cough* What's going on?"

"Not sure. There was some experiment here, it blew up, and now I look and sound like a teenager. You seem to have de-aged a bit too." He helped Bucky up, demonstrating that Bucky was considerably shorter than him. Bucky's nose was about level with Steve's chin. Bucky gasped, right arm shooting up to grasp his left shoulder. "What? Bucky, what's-" Bucky gave a snort of laughter at the squeak in Steve's voice. Steve glared in response.

"My arm is heavy." Steve looked again, and struggled to contain his laughter. The explosion that had shrunk them down, that had de-aged them, as well as not affecting their clothes had also had no effect on Bucky's arm, leaving him in a twelve year old body with an adult-sized arm. The more Steve looked the more comical it was, and he couldn't contain his laughter. Bucky shoved him. "Shut up, punk."

"I'm sorry, you just look so- Quit laughing, jerk!" Bucky ducked Steve's shove, laughing at his squeaky voice. Steve began laughing anew at Bucky's arm, and they took a few more swipes at each other before Bucky's metal arm yanked too hard on the shoulder and he gasped in pain. Laughter forgotten, Steve looked Bucky up and down as he clutched at his left arm. An idea came to him, and he got Bucky to remove his hoodie which he then used as a makeshift sling, supporting the metal arm in such a way that the weight was focussed on the elbow rather than the shoulder. The hoodie wasn't an ideal sling, but it was large enough that Steve could tie it off to make it more supportive. "How's that?"

"Better, thanks." Bucky rubbed at his shoulder.

"So what were you doin' here, Buck?"

"I- er, I followed you. Have been for a while. Since I gave up on my mission." He cleared his throat, uncomfortable with the route the conversation was taking. "So, Captain. What next?" A small smile flickered across Steve's face when Bucky addressed him as Captain, then was swiftly replaced by a frown as he tried to figure out the next step.

"Sam. We need to find Sam, and then the rest of the Avengers," he reasoned. "Sam was closest, so he should be easiest to find, and then once we find Tony and Bruce-" His eyes widened as the implications of Bruce being involved in the explosion hit him. "Shit, I hope Tony got Bruce out before the explosion." Bucky frowned, not quite understanding.

"Which one's Bruce?"

"Hulk." Bucky's expression flipped instantaneously from confused to alarmed. He looked Steve up and down, then replied,

"The serum is still affecting you, so he would still be..." That wasn't quite what Steve had been worrying about, but of course, it stood to reason that everyone else would have been affected in a similar way.

"He would still turn into Hulk, but Hulk would be smaller? Younger?" he asked, eyebrows knotted as he tried to figure it out. Bucky tilted his head to one side as he thought, then shook his head.

"No point worrying about that. Let's find... Sam? That's the bird-dude right?"

"Falcon." Steve nodded. "I know he was somewhere close by, but I'm not sure exactly..." He looked around. Even if he had known, finding his bearings was proving difficult in the aftermath. Bucky slowly turned, frowning, then stopped and pointed forward.

"I think there was a window in that direction, maybe he went out to stretch his wings." Steve raised an eyebrow at Bucky, who held his straight face for a few seconds before sniggering. Steve rolled his eyes.

"Well, it's about the only lead we've got, c'mon." Steve led the way, struggling through the rubble in the direction Bucky had indicated. Bucky's sense of direction had always been good, and Steve figured Hydra probably improved it for their Winter Soldier. Soon they could see the window ahead, and Steve heard a slight crackle from his comms. Clearly it was just inside the building that comms were down, and at the window he might be able to get a signal.

When they reached the window, Bucky turned his back to look around the interior of the building, hoping to spot something that might clue them in on where to look next. Steve leaned on the window ledge and tried to contact Sam.

"Sam? Sam are you there?" He paused, waiting for the response, and was just about to ask again when he heard more crackling and a voice, only just discernible as that of a child.

_"Steve? Steve, is that you?"_

"Sam?"

 _"Yeah, and I got a problem buddy... Look down and to your left..."_ Frowning, Steve looked and gave a shout of alarm when he saw the ten year old form of Sam Wilson, clinging desperately to his wings, which had jammed on a drainpipe as Sam fell from a window. It didn't look like the drainpipe would hold up much longer, and the same went for Sam's grip on the wings. Bucky peered over Steve's shoulder, then scanned Sam's surroundings, calculating an escape route for him.

"Tell him to try and swing himself and jump towards that awning," he said, pointing towards the awning above a café a few metres to Sam's right, and several stories below him.

"Sam? Do you see the awning to your right?"

_"The brown and white? Yeah, I see it."_

"Think you can make the jump?"

 _"I dunno... I'm not as old as I used to be..."_ Steve smirked.

"You can do it, buddy, come on..." He watched, continuing to give words of encouragement, as Sam tried to push himself along the wall, away from the awning, building up for a swing towards it. A small crowd had gathered below him, and some of them seemed to be preparing to catch the little boy when he fell.

There was a sudden jolt as the drainpipe began to give, and Sam pushed off quickly, swinging vaguely in the right direction. He released the wings and they fell to the ground behind him, as he fell through the air, arms wind-milling wildly. Steve gauged the trajectory and whispered, "He won't make it..."

Sam seemed to find the same conclusion, and began to reach, and just managed to get one arm on the edge of the awning. Steve breathed a sigh of relief as Sam grabbed on, hanging for a moment, before dropping the final distance to the ground. He looked up at Steve, panting hard.

_"That was... I better never have to do that again. You oughta go find the others... Where's Hill? Shouldn't her team be moving in by now?"_

Before Steve could respond, Hill's voice crackled over the comms, _"We're just approaching now... What happened? Why do you guys sound-?"_

"Something in the explosion seems to have... de-aged everyone... Well, me, Sam and Bucky at least. Hill, pick Sam up, then get a team up here to help go through the rubble. ... Did Tony get Bruce out?"

_"That's a negative, Captain."_

" _Shit._ Okay, well that means we probably have a miniature Hulk running around up here... Comms don't seem to be working inside, so I might not be able to check in for a while." With that he pushed away from the window, striking out towards the epicentre of the explosion before Hill could try and stop him from going back in. He may be a teenager now, but he was still Steve Rogers, and nothing was going to stop him going into a potentially lethal situation to rescue his friends. Bucky didn't even hesitate to follow him, even though having de-aged further, coupled with the issues with the metal arm meant he had no chance of keeping Steve from doing something horrendously stupid.

As Bucky was struggling over a particularly difficult bit of rubble, Steve glanced back at him and said, "You know, you don't have to stick around. If the arm is an issue, you-"

"I'm staying." After a few moments more struggling while Steve watched, smirk plastered across his face, Bucky looked up and admitted, "I could use a hand though." Steve reached up and helped him get the rest of the way down from the rubble.

"Hopefully Bruce and Tony can come up with a way to turn us back, and until they do Tony can probably sort you out a more... proportionally appropriate arm." Bucky pulled a face, then tensed suddenly as a small child cried somewhere off to their left. The cry was hushed quickly and quietly, only just audible to the supersoldiers' enhanced hearing. They began moving in the direction of the noise, Steve calling out, "Hello? Are you alright? Who's there?"

A shot was fired at Steve's feet, stopping him in his tracks. "Depends who's asking." The voice was female, and quite young. Steve took a guess as to the owner.

"Nat? Nat, it's me, it's Steve..." He glanced back at Bucky. "And Bucky is with me, but he won't hurt you... Is Clint...?" Natasha stepped forward, silencing Steve's question. She looked about eight or nine years old, and in her arms was a toddler, still clutching his bow. Steve's eyes widened.

"Well that hardly seems fair," Natasha complained as she looked Steve up and down. "You're what, fourteen? And he's about twelve? And here I am, eight years old, stuck with a three year old best friend. You find anyone else yet?"

"Sam. He's around ten, but I think he had it worse than you." Natasha challenged this with a cocked eyebrow, so Steve elaborated, "He fell out a window, and his wings were too big for him. He's lucky to have survived the fall. Hill's on the ground, I told her to pick him up. She should be sending a team up to assist here, maybe you should go meet them with Clint." For a moment it seemed like she would protest, then Clint started to cry again, scared and confused. She cuddled him close, murmuring softly to him.

"Can you point me in the direction of the stairs? I lost my bearings a bit." Bucky pointed, and she started off in that direction.

"Oh, and Nat? Tony never got Bruce out, so be careful. You encounter the Hulk..."

"Try to stay out of sight, and scream if he spots me?" she suggested. Steve nodded. They'd been working on a way to get Bruce back, but so far had had no success, and under the circumstances it seemed even less likely to work. "I think they went off in that direction, so I'm probably safe. And Thor went that way." Steve nodded his thanks as Natasha headed off towards the stairs, bouncing Clint on her hip as she walked. Steve had to admit, he was surprised she seemed to be so good with kids. He hadn't expected it of Natasha. He turned back to Bucky just as he asked,

"So who are we going after first?" Steve thought for a moment.

"Tony's armour might have protected him from the explosion, so let's find him first." Bucky nodded.

"Lead on, Captain," he said with a mock salute. Steve shoved him playfully, grinning, as he walked past, leading off in the direction that would supposedly lead them to Bruce and Tony. After a little while of scrambling over rubble, Steve spotted a flash of red up ahead.

"Tony?" he called. There was no response. Keeping his eyes on the red as much as he could, Steve forged ahead, concerned. He was sure that was the armour, and there was no movement. He pushed aside a bit of rubble from the doorway, to reveal the Iron Man suit lying on its back, motionless. There was no glow from the arc reactor in the chest, and the room felt eerily quiet. Bucky looked around at the room and murmured, "The destruction is different in here... This wasn't caused by the explosion." Steve gritted his teeth.

"Hulk." He approached the suit, worried. "Tony? Are you in there?" He knelt by the suit and pulled the face mask off. Empty. But with the face mask removed, he could hear something. A quiet gurgling. Steve frowned, and glanced at Bucky in confusion. Bucky stepped forward and pulled on the chest plates. Steve joined in, and after a bit of straining they succeeded in opening the chest cavity, revealing a nine month old baby inside.

"Guess the armour didn't help him." Steve didn't respond at first, just stared down at the infant form of his teammate. He swallowed, then eventually reached in and scooped up the baby.

"We can't leave him here. Hill's team can retrieve the armour later. We'd better-"

A scream cut him off before he could suggest getting Tony to safety before continuing their search for Thor and Hulk. It wasn't Natasha, and Steve and Bucky took off in pursuit immediately, Steve cuddling Tony close and hoping that somehow he could keep the baby safe.

The source of the scream was not quite what they expected. Mjolnir was lying atop a pile of rubble, and underneath that rubble, a six year old Thor. Or at least, he looked six by Midgardian standards. Who knew what age he was for an Asgardian. Thor was the source of the scream. He was trying to call the hammer to him, as it was preventing him from moving the rubble currently crushing his right arm, but little Thor was no longer recognised as worthy by the hammer.

"Thor! Thor, be quiet, you'll attract the Hulk!" hissed Steve, skidding to his knees by Thor, doing his best to protect Tony's ears. Thor raised his head, quieting his screams, but Tony took them up. Steve groaned, hanging his head.

"Perhaps the Hulk can free me from this mess," panted Thor, but Steve shook his head.

"You know as well as I do Hulk can't lift your hammer. Do you think you could, if you were able to reach it?" he asked, although he thought he already knew the answer. His fears were confirmed when Thor shook his head. Steve sighed. "Alright, we'll have to just try and pull your arm out. Bucky, can you hold Tony for me?" Without waiting for a response, Steve placed the wailing child in Bucky's sling, adjusting it so Tony was supported and Bucky's arm wasn't pulling on his shoulder too much. Surprisingly, Tony settled down quickly in Bucky's hold, as the nervous twelve year old rocked him gently, bring his real hand round to cup Tony's head.

Steve smiled, then returned to Thor's side, gripping his shoulder, and bracing against the rubble, trying to help work Thor's arm out. It quickly became obvious that it was no use. The rubble had to be lifted to free Thor's arm, and it couldn't be lifted without lifting the hammer. Still Steve struggled on, until a growl from behind alerted him to the Hulk's arrival. He swallowed, and turned to see Hulk, significantly smaller than usual. As in, right now it was smaller than Steve. Only just, but definitely smaller than him. It was still large enough around the middle that Bruce's trousers stayed up, and Bruce's shirt seemed to be more or less intact for once. It growled, taking a swipe at Bucky, who had the sense to duck, rolling away while still keeping Tony safe and secure in his arms. Steve glanced at the rubble between Thor's arm and Mjolnir, and decided on a risky strategy.

"Hey! Over here!" he called, attracting Hulk's attention as he stood, waving his arms to make sure Hulk saw him. Hulk growled, and leapt at Steve. Steve ducked out of the way, and Hulk smashed into the rubble, breaking off enough that Thor could pull his arm free and stumble backwards. Hulk roared, and grabbed a chunk of rubble to throw at Steve.

"Genius, Steve! Make the rage monster even more pissed off! What a brilliant plan!" yelled Bucky, voice dripping with sarcasm.

"I got Thor free, didn't I? Now I just need to-" he cut off as Hulk threw more rubble in his direction. "Bucky, get Thor and Tony out! I'll find a way to calm down Hulk, just get them safe!" he shouted over the sound of Hulk growling and smashing his way through the rubble. He pulled the shield from his back, considering its possible uses in this situation. Bucky reluctantly retreated as instructed, as Steve ran off in pursuit of Hulk, who was heading towards a broken window just visible in the distance. As they neared the window, Steve came up with another ridiculously stupid plan, and since it was all he had, he went for it.

He grabbed Hulk around the neck from behind, and charged at the window, shield first. They smashed through together, and fell down, down, down to the alley below. The shield impacted first, jarring Steve's shoulder slightly, but the Vibranium did its job, deflecting most of the impact and saving Steve from serious injury. Hulk collapsed on top of Steve, the fall proving too much for this younger version of the monster.

"Hill?"

_"We saw that, we're on our way. Is Hulk down?"_

"Looks that way. Has anyone been able to lift the hammer? Or is it just staying there until we can get back to our real ages?"

_"Your friend Barnes managed it. Thor is throwing a tantrum. You sure we can trust Barnes?"_

"Well, if he can lift the damn hammer... And besides that, he's my best friend, and I would trust him with my life. Already have, several times. He's good." Steve got to his feet shakily. He'd fallen a similar distance when escaping from the elevator at the SHIELD base, but he'd been older, stronger then, and he hadn't had Hulk land on top of him either. Hill's van parked at the end of the alley, and her team ran up to carry Hulk and escort the Captain back to the tower.

\- - - -

Three days after the explosion, Steve was assisting Bucky in changing Tony's diaper when there was a crash from down the hall, followed by a lot of shrieking. Moments later, Thor came sprinting in.

"Hulk?" Steve asked as he panted for breath. He nodded, and Steve glanced at Bucky. "You okay to finish here?"

"Yeah, I can manage." Steve was running off before Bucky had finished his sentence. "Thor, can you hold Tony still while I fasten this?" He jerked his left shoulder, momentarily forgetting that he didn't have an arm on that side to gesture with. Without Tony to build a more appropriately sized arm, he'd had to make do with the over-sized one being removed, and was trying to cope with just one arm.

Thor climbed up onto a stool next to Bucky and helped him out, keeping Tony from squirming too much while Bucky finished securing the diaper and sorted Tony's clothes over the top. Thor then entertained Tony while Bucky cleaned up.

"D'you think it's safe to head back in now?" asked Bucky.

"Maybe. If not, they might need your help."

"I hope not. It feels so wrong to use the hammer against a four year old." Bucky scooped Tony up, and headed down the hall with Thor. Thor pushed the door open, revealing Hulk curled in a corner, glaring at Steve as the fourteen year old supersoldier approached cautiously, talking to him, trying to keep him calm. On the other side of the room, Natasha was trying to soothe Clint while simultaneously scolding Sam. Bucky approached them, leaving Steve to deal with Hulk.

"What happened?" Bucky asked, keeping his voice low so as not to upset the Hulk.

"What do you think happened? Sam was being loud and upsetting Bruce, he kept trying to make Thor wrestle, then he decided to try and take Clint's bow. Clint started crying, and Bruce lost control." She glared at Sam, who was looking at the floor guiltily. Bucky frowned at him.

"So you were winding Bruce up. Deliberately?" Sam's only response was a gulp. "Sam, do you think we don't have enough problems to deal with right now? We're all finding this hard, being de-aged, and we don't know how to fix it. Without us War Machine is the closest thing to a superhero out there, we have sixteen civilians downstairs who've been affected by this, same as us, and we need to keep this quiet. We do _not_ need the added trouble of you upsetting Bruce and endangering everyone in this tower. If you can't learn to behave yourself, there _will_ be consequences. Understand?" Sam nodded, still looking at the floor. "Good. Now apologise to Clint and Natasha, and when Bruce has calmed down again I want you to apologise to him as well." Again Sam nodded, and he glanced up at Natasha as he mumbled,

"Sorry, 'Tasha. Sorry, Clint." He did sound genuinely sorry. Bucky nodded his approval.

"Good. Now go sit in the corner until you can apologise to Bruce." Sam looked up, dismayed. Bucky silenced his protests before they could begin with a stern look. He used his head to indicate which corner Sam should go to, and Sam glared for a moment, before stomping off to the corner, throwing himself down and folding his arms crossly. A low growl from the other side of the room alerted them to Hulk's displeasure at the noise level, and everyone froze for a moment. When nothing else happened, they relaxed, and found quiet activities to do until Hulk shrunk down again. Thor resumed the colouring he'd been doing earlier, Natasha got some headphones for Clint and a tablet with games for him, and Bucky sat down with Tony and played with the stuffed animals they'd acquired since the explosion.

It took about half an hour for Hulk to shrink down again, at which point Steve brought him over to the low table where Thor was colouring. Bucky began to ask if Sam should come apologise now, but Steve shook his head. Bruce still needed some time. Bruce sat next to Thor and started colouring too, finding it therapeutic after Hulking-out. Steve went over to the corner to talk to Sam, taking a much gentler approach than Bucky. But in the end, he told Sam to stay where he was until Bruce was ready, then left him on his own and went to help Natasha and Bucky look after the little ones.

A short while later, there was a knock on the door, and without waiting for a response, Hill entered.

"So how is everyone? I've brought some people here, some of SHIELD's finest, and they should be able to help."

"I thought we shut down SHIELD," Steve began as he got to his feet. Hill cut him off before he could continue.

"Fury appointed a new director, who was instructed to rebuild SHIELD. You remember Phil Coulson..." She stepped aside, and Coulson walked in, followed by a group of people. Coulson smiled round at everyone and silenced the exclamations of surprise that he was alive.

"Nice to see you all again. And a couple of new faces..." He frowned as he spotted Sam still sat in the corner, but continued, "Yes, I did die, but Fury went to extreme lengths to bring me back. Allow me to introduce my team: May, Simmons, Fitz, Skye, Trip, Mack, Bobbi and Hunter." He pointed at each person as he introduced them, and most of them waved or said hello, and Hunter pointed to Sam and asked,

"Why is he sat in the corner?"

"He upset Bruce, so he's sat in the corner until Bruce is calm enough for him to apologise," Bucky explained, getting to his feet. He approached Trip and said, "You look somewhat familiar." Trip looked him up and down.

"Bucky Barnes right? You knew my grandfather, Gabe Jones." Bucky nodded, and Steve stood too, also approaching Trip.

"Gabe's grandson, huh? Nice to meet you," he said, shaking Trip's hand. Trip grinned.

"Well, it's an honour to meet you, both of you. Grandpa always spoke highly of you." Bucky smiled weakly, made uncomfortable by references to a past he only half remembered. He turned to Coulson.

"Is there anyone on your team who might be able to sort me out with a new arm? The one Hydra kitted me out with is too large now."

"We have the old one in the workshop if it would help. I had planned to have Tony build a new one, but right now he can't really build anything more complicated than a tower of bricks," Steve added, gesturing at Tony, who was sucking on the foot of his stuffed toy rabbit. Skye spluttered as she saw him.

"You put him in an Iron Man baby-grow?"

In unison Bucky and Steve pointed at Natasha and said, "It was her idea." Coulson smiled and responded to Bucky's question.

"Fitz and Mack can probably manage that for you."

"Just show us to the workshop and we'll see what we can do," Mack said. Steve grimaced.

"That could be a problem. Also if any of you intend to use the lab to find a way to undo this..."

"Why? What's the problem?" asked Coulson.

"Jarvis isn't being very cooperative since the explosion. Keeps locking us out of places, and talking to him doesn't seem to be working."

"Perhaps if Skye could hack into his systems, she could convince him to work with us?" Coulson suggested. Skye frowned.

"Um, who... or what... is Jarvis?" she asked, confused.

"Jarvis is Mr Stark's-"

"Shhh, don't say the S-word!" hissed Steve, but it was too late. Tony started bawling loudly, and Bucky rushed over, scooping him up and shushing him, rocking him back and forth. Coulson and his team looked a little taken aback, so Steve explained, "For some reason, Tony bursts into tears any time someone mentions his last name. Bruce reckons it's to do with how much he can remember..."

Natasha chimed in, "The little ones have less memory of being grown-ups." At this point Clint noticed the newcomers, having been too absorbed in his game before, and he ran forward, throwing his arms around Coulson's leg and shouting, "Phiy!" joyously. Bruce and Thor also stood up from their colouring, Thor coming forward to greet everyone, and Bruce hanging back, nervous of losing control again. Sam approached him to apologise as Coulson picked up Clint and fussed over the three year old.

"Bruce?" he said quietly. Bruce jumped, and turned to look at Sam, suspicious. He was tense, fists clenching and unclenching. Sam ploughed on with his apology, despite the warning signs that Bruce was on the verge of losing control. "I'm sorry for being loud and upsetting you. It wasn't nice of me. We good?" He reached out to touch Bruce's arm, but was abruptly pulled back. He looked up to see May looking at him sternly. She pulled him away from Bruce as Steve came over, talking quietly to Bruce, trying to calm him down. Bruce backed away, shaking his head.

"Do you need to go next door?" Steve asked, referring to the padded room that had been set up for when they couldn't control the Hulk. If he lost control outside of that room, sometimes they could calm him down, but if they couldn't Bucky would use Mjolnir to direct Hulk into the room, and lock him in there until he calmed down.

Bruce nodded, and allowed Steve to lead him through to the room. Moments after Steve locked the door, it shook as Hulk impacted with the other side. He returned to the main room, where Sam was being scolded by Natasha once more. Steve went up to Coulson.

"We need to fix this. Do you think your team can find a way?"

"If there is one, then my team will find it. In the mean time, we can help with looking after the younger ones, we'll do what we can for Dr Banner, Mack and Fitz will sort out a new arm for Sergeant Barnes, and if any urgent Avengers business comes up, we'll deal with it."

Hunter looked up from where Thor was showing him his drawings. "Wait, did I hear that right? You're gonna get us to deal with Avengers stuff? Are you serious?!" Coulson looked at him.

"When I say urgent Avengers business, I mean things like invasions, attacks. Emergency situations that can't be left until we can resize Earth's mightiest heroes. We have Colonel Rhodes to call on, but we may need a bigger response team than that. If you don't want to help out on such an occasion, should one arise, that's fine. You can stay behind and babysit. But we need a response team."

Steve looked around at Coulson's team. "You sure your team can handle that?"

"They'll have to. But they are good, Captain. I can promise you that."

"What about Mike Peterson?" asked Skye. "Is he gonna be part of your emergency response team? The Substitute Avengers?" Bucky smirked at the name.

"If necessary, yes. Hopefully we won't need a substitute at all. For now, Skye, we need you to talk to Jarvis, Tony's computer system, and see if you can get him to cooperate. Sergeant Barnes, see if you can get Fitz and Mack into the workshop to work on your arm. Simmons, what do you need to get started on figuring this out?"

"I'd like to use the dwarves to take some readings at the site of the explosion, and then I need to do some tests on everyone affected. I'll need to access the labs for testing, so it'll have to wait until Jarvis is cooperating. And any information that can be gleaned from the Iron Man suit could be useful too, but again, that'll have to wait."

"Alright. Bobbi, you go with Simmons to the explosion site. As for the rest of us..."

"If you don't want to babysit, I can show you to the training rooms," Steve suggested, and May decided to take him up on the offer. Everyone else either stayed in the room or followed whatever orders Coulson had given them. Bucky took Tony with him so Jarvis would let them into the workshop. A while later, after Skye had convinced Jarvis to cooperate, Bucky returned to the room. He stuck his head around the door frame and said,

"Can someone lend me a hand, Tony needs his diaper changing. It's at least a two-handed job, and Mack and Fitz won't have a new arm for me until tomorrow." Hunter volunteered, much to the surprise of those who knew him. But as it turned out, Hunter was pretty good with kids, and Bucky was very grateful of his help. When they returned, Nat and Skye both had their phones out, filming Clint as he sat on Coulson's lap, babbling away. Bucky rolled his eyes. He passed Tony over to Hunter. "I'm gonna go find Stevie, look after Tony for me." As he started to walk away, Tony stretched his arms out and called,

"Bu-bu!" Bucky froze. Slowly he turned and looked at Tony, who repeated himself. "Bu-bu."

"I don't think he wants you to go, mate," said Hunter. Nat grinned.

"Yeah, stick around Bu-bu!" she teased. Bucky glared. His arm tensed, and suddenly Mjolnir flew across the room and into his hand. He looked at it in surprise.

"Wait, hang on I think I figured it out..." he said. He put the hammer down, and stepped away, and tried to call it. So far, he'd only ever succeeded in summoning the hammer accidentally, and hadn't quite figured out exactly how to do it. He frowned with concentration. The hammer stayed put. "Urgh!" Bucky kicked it, frustrated. "Thor, what the hell is wrong with your stupid magic hammer?! Why does it only ever come when I don't actually want it?!" He gesticulated angrily, and suddenly the hammer flew up into his grip again. He made a noise of frustration, and made to fling the hammer aside. Before he could, Tony giggled, distracting him. After a few deep breaths he put the hammer down by the wall and left it. He picked Tony up again, cuddling him and attempting to tickle him while still keeping a secure grip. Tony squirmed a bit, giggling some more. Hunter put out a hand behind him, just in case he managed to squirm out of Bucky's grip.

"You seem to be managing pretty well with one arm," Hunter observed.

"Yeah, but I'll be glad when I can have two again." After tickling Tony for a few more minutes Bucky put him back in Hunter's arms and said, "Okay, Tony, I'm gonna go find Stevie, you stay here with Hunter, okay? I'll be back soon." Without even thinking he placed a kiss on Tony's head and left, ignoring the click of Natasha's camera.

\- - - -

When Simmons and Bobbi got back from collecting data they went straight to the lab. Simmons started working through the data, assisted by Jarvis, who was happy to help after his 'discussion' with Skye. The next day Simmons asked for the Avengers to come in small groups to undergo the tests she needed to figure out what had happened. Bucky went first with Tony and Thor, then Steve took Sam and Bruce (Simmons insisted on having May nearby as a precaution while she tested Bruce), and finally Natasha and Clint. She then moved on to the sixteen civilians who weren't evacuated quickly enough. After Mack and Fitz finished work on Bucky's arm they gained Jarvis' permission to work on the suit that was recovered from the building, fixing it up and seeing if it could tell them anything about what happened.

Bruce assisted Simmons when he could, finding that working in the lab could be quite calming. Steve was told rather emphatically by Coulson that he absolutely could not fight if the need arose, so he decided to pass the shield temporarily to Trip, and he spent much time training him with using the shield. Coulson's team all tried their hand at lifting Mjolnir, and Thor was very satisfied that none of them could shift it. Having told Steve he wasn't allowed to fight, Coulson also had to say that even though Bucky could wield the hammer he was also banned from fighting, which Bucky actually didn't mind. There was talk of someone training to use Sam's wings, but they decided it would be too complicated. Coulson's team managed to find ways to keep Sam entertained without him resorting to winding Bruce up, and Natasha filmed nearly everything, claiming that it was necessary to make lots of videos to embarrass Clint and Tony with when they grew up. Steve had a feeling Tony would be particularly embarrassed by 'Bu-bu', and the mere fact that he seemed most at home in the arms of the man who killed his parents. He also became quite attached to Hunter, which they suspected was down to the accent, reminding him vaguely of Edwin Jarvis.

Eight days after the arrival of Coulson and his team, Bucky had convinced Hunter to take Tony for a while (or rather convinced Tony to stay with Hunter) and was play-wrestling with Steve like they had when they were growing up when Simmons came rushing in excitedly.

"Good news?" Coulson asked, smiling fondly at the bouncing biochemist.

"I've cross-referenced the test results for all the affected parties, and examined evidence from the blast zone and from the suit, and what I discovered, it's simply extraordinary, look-" She activated a large screen on the wall, displaying an assortment of images and diagrams, and began talking through them. Bucky glanced around, checking that everyone else was as confused as he was. Simmons was slightly breathless by the time she reached the end of her explanation, and she looked around, her excitement dimming slightly at the cluelessness most of her audience was displaying. "It's... nano-"

"Simmons, I'm not gonna pretend to have understood half of what you just said," Bucky cut her off before she could start again, "but are you saying you've figured out the cause of... this?" His gesture included all the de-aged people in the room.

"Yes. It's quite simple really, these-"

"Can you fix it?" Sam interrupted, for the first time voicing the fear that all of them had felt secretly, deep inside. The fear that this de-ageing would prove irreversible. The room feel eerily silent for a moment, even Clint and Tony pausing in the game they were playing, supervised by Hunter.

"Possibly. I have a theory, well less than that, more of an idea really, there's still so much more to do, and I don't know how on Earth I'm supposed to test it, assuming we can actually-"

"Jemma!" Coulson interrupted. She stopped and looked at him, taking a deep breath.

"I'm confident that it should be possible to reverse the effects, but it will take some time to develop a viable solution."

"Okay," and the entire room seemed to relax, knowing that eventually, the situation could be remedied. "What do you need?" asked Coulson.

"Fitz." Coulson nodded.

"Alright, Fitz-Simmons, get to work on this idea, and let me know if there's anything else you need. Everyone else, as you were."

As Fitz-Simmons left, returning to the lab to get to work on whatever Simmons' idea was, the rest of the room was buzzing with excitement. Natasha returned to snapping photos of Tony and Clint, now with a much brighter smile on her face. Bruce was almost literally buzzing as he perused the data Simmons had presented, taking his time to explore her findings and reach the level of understanding that would have been instant for him before the explosion. Sam resumed his game of aeroplane with Trip, leaping onto the man's back with renewed vigour now he was reassured that he would be soaring through the skies again in the not too distant future. Thor went back to his animated conversation with Skye describing the beauty of Asgard, even more enthusiastic knowing that he would be able to return (his youth by Asgardian standards meant he was incapable of summoning the Bifrost) and Coulson went over to join them. Bucky and Steve decided they'd had enough of play-wrestling, and instead headed over to the TV, having Jarvis put on a Disney movie as they flopped down on the sofa, Steve sprawling across Bucky's lap. Bucky rolled his eyes and began to softly run his metal fingers through Steve's hair.

\- - - -

It took a few days for Fitz-Simmons to work out how to implement their idea, and another week after that to construct the contraption. When it was complete, the Avengers and Coulson's team gathered in the lab, eyeing the machine with varying degrees of uncertainty.

"You're sure this thing will work?" asked Steve, turning his gaze to the scientists.

"We've run as many simulations as we can, and so we're as sure as we can be before testing it..." Simmons began, sounding slightly uncertain towards the end.

"I sense a 'but' coming," Natasha commented drily, bouncing Clint on her hip.

"The only way to test it is for someone who was de-aged in the explosion to, t-to go into the machine, and we don't know... it might not be safe." Fitz stuttered through the sentence, everyone having learnt to be patient with him.

"And quite frankly, every simulation we've run for re-ageing Dr Banner has resulted in... well you can probably imagine..."

"So we do him last and evacuate the building beforehand?" Sam suggested, ducking behind Skye to avoid May's glare.

"Well, actually, we were thinking that maybe, maybe Tony might, er... might... er... he might improve the machine. When he's been re-aged. He can help us make it better." Simmons joined in with the last sentence, the pair beginning to regain the connection that had been lost with Fitz's brain damage.

"So you want to do Tony early on, but you probably want to test with someone else first, right?" Bucky looked around for clarification. He saw the look in Steve's eyes, and before the punk could say anything stupid, Bucky volunteered, "Well let's get this over with then. I should probably take this arm off and change into some larger clothes, right?" Simmons looked rather taken aback.

"Uh, are you sure you want to do this? I'd have thought... after Hydra you'd-"

"You thought I'd have had enough of people experimenting on me? Well you'd be right. But I have to do this eventually, and I'd rather get it over with. And I don't think I could just stand by and watch while someone else risks themselves." This last bit was directed mostly at Steve, the tone implying that Bucky had already had enough of Steve risking himself. Steve had the grace to look a little sheepish, but he was also worried.

"When you say it might not be safe... could he die?" he asked, clearly not prepared to lose his best friend again.

"It's a rather remote possibility, but yes." Bucky swallowed, but he was determined to go first.

"Hydra's experiments made me stronger, so I have a better chance of surviving, right?" He paused, before adding in his second argument, "And you guys are all heroes. I'm not. So I'm more... expendable." The look on Steve's face made him regret his words immediately, but it was Coulson who reassured him.

"Sergeant Barnes, you are a hero. You are also probably the longest serving prisoner of war in the world. Your life is not worth any less because of that. But if you're still sure you want to go first," Bucky nodded vigorously, "okay, well then here are some larger clothes, you can change through there, and then Fitz and Mack can help remove your arm when you come back in." He handed over the clothes and pointed Bucky through a door. Bucky placed Tony in Hunter's arms, placed a quick kiss on his forehead then left, dodging Steve's gaze. When he returned, it took Mack and Fitz a few minutes to remove his arm, during which Bucky glared at Natasha and Sam, both of whom were stifling giggles at the sight of Bucky in comically large clothing. Once he was free of the arm, Simmons guided him into the large metal box where he would hopefully be changed back. There was a window in the side so they could see him, and he looked at all of them gathered there.

"Do I have to have an audience?" he asked, feeling self-conscious. Simmons smiled at him as she settled him on the seat in the middle of the box, hooking up various monitoring equipment.

"We need to see in to monitor you, make sure everything's alright. I can ask the others to leave though."

"Steve can stay, and whoever you need to stay for monitoring, but everyone else needs to go. Especially Tony." He tried to keep the fear out of his voice, but still it shook slightly. Simmons nodded, and headed outside, locking the door behind her. Bucky watched as she appeared in the window and began shooing everyone out, except for Steve, Fitz, Coulson and Bruce. He saw Tony start to cry, and waved at the baby, trying to convince him to leave. He couldn't bear the thought of Tony watching, especially if something bad should happen to him. He couldn't do that to the baby. Couldn't let him watch. Eventually Simmons got everyone out, and then she pressed a button to be able to speak to Bucky.

"Alright, let's get this started then. We have an emergency stop button, but I have no idea how effective it will be. Or if it will even work. And it might make the situation even harder to remedy."

"You're really not helping me feel any more confident about this." Bucky's voice was projected to the outside of the box now the mic was turned on. Steve smiled, trying to hide his concern, and failing miserably. Bucky smiled back, doing a slightly better job of hiding his fear of what was to come.

"Okay then, Fitz, turn it on." Simmons looked at Fitz, clearly too nervous of what might be about to happen to do it herself. Fitz looked nervously at Bucky, who gave him a reassuring nod, before he pressed the button, starting up the machine.

There was a whirring noise, that started quite loud and just got louder, and Bucky looked around nervously. Other noises joined in the mix, clanks and bangs, grinding and hissing, until it was impossible to pick any individual noise out of the cacophony. A bright light appeared above the window, and grew brighter and brighter, forcing Bucky to cover his eyes. Then without warning the light seemed to explode outwards, the noises cut out, and Bucky found himself being thrown backwards. For a moment, everything went black.

His head was ringing, his vision blurred, and his entire body felt sore. But when his vision cleared, he looked down at himself, and saw he was back in his 29 year old body. Distantly he heard the sound of the door unlocking, and then Fitz and Simmons were fussing over him, Steve was hovering worriedly behind them, and he was being helped out of the chair. They guided him out of the box, and after a few minutes his hearing recovered properly and his head stopped spinning. He cut off Simmons' babbling with a sharp, "Either do something about the noise in there, or make sure Tony has ear protection. If it weren't for Hydra's experiments, I would be deaf after that." He thought for a moment, then added, "And maybe get some more padding in that chair, I got thrown against it pretty hard." Simmons breathed a sigh of relief.

"Okay, we'll get working on that. Are you injured at all?" Bucky grimaced, stretched out a bit, testing his body.

"I feel like a walking bruise, but I don't think there's any serious damage. You're definitely right about it being a bad idea to put Bruce in that thing, there's no way he'd make it through without Hulking out. And I doubt any of us can talk down a fully grown Hulk." He glanced across at Bruce, who was perched on a worktop nodding his agreement, glasses slipping down his nose. Coulson was hovering by the door, waiting to let everyone else back in. Bucky spotted him and nodded. "Go ahead, let 'em in."

"Bu-bu!" Tony's insistent cries filled the room the second Coulson opened the door. But it was Mack that entered the room first, holding Bucky's original arm.

"Thought you might be wanting this," he beamed, practically bouncing over to Bucky's side. Bucky watched the others filing in behind him, all looking excited and relieved to see him in one piece, back to his proper size. For a moment he was concerned that Tony wouldn't recognise him, but the second Hunter rounded the door frame and Bucky came into Tony's line of sight, the baby reached out his arms and his cries turned from petulant to overjoyed. Hunter brought him over and Bucky carefully reached out with his right arm while Mack and Fitz began working on reattaching the metal one. He cuddled the baby to his chest, placing a gentle kiss to the top of his head. As usual the kiss was accompanied by the click of Natasha's camera. Bucky grimaced this time.

"With all these pictures you're taking of us, he's gonna hate me when he gets aged up."

"Well maybe you should stop kissing him. He might even remember it without my help."

"I doubt it, I mean, how much do you remember from when you were that age?" Bruce pointed out, swinging his legs where they hung off the edge of the desk.

"So are you gonna put Tony in now, or...?" Skye asked, and Bucky cuddled Tony closer, protective of the baby he'd looked after since the explosion. Simmons shook her head.

"It'll take a few hours to reset the machine, and there are a couple of adjustments we need to make before Tony can go in. Just some minor safety concerns that Sergeant Barnes has raised, things that didn't harm him but which could be a lot worse for Tony."

"Like what?" Hunter asked, stretching out a hand to stroke Tony's head, also feeling rather protective.

"Padding and ear protection. It got real loud in there, and I got thrown back against the chair pretty hard. Could do Tony some serious - OW!" He flinched away from Mack and Fitz, the final attachment of the arm sending pain lacing through his shoulder. He flexed the metal arm, checking it hadn't been damaged at all. Surprisingly, it was alright. Could probably use a little fine-tuning, but he could manage for now.

\- - - -

A few hours later, Bucky received a text from Steve, letting him know that the machine was ready for Tony. They hadn't been allowed to leave the Tower since the explosion, but Bucky had convinced Coulson to let him take Tony out for a walk. Wearing a hoodie, with a glove on his left hand, nothing looked out of place about Bucky, and who was going to suspect that the nine month old baby in an Iron Man baby-grow he was carrying was Tony Stark? He was confident that Tony would not remember this, and that Tony would hate him when he aged up, so he wanted to make the most of the time they had left. Preferably without Natasha and her camera recording every kiss, every cuddle, every laugh, everything they did together that could be used to embarrass or blackmail them later. All the things that would make Tony hate him even more than he would have anyway. Because obviously Tony would hate Bucky, he'd killed the man's parents after all, and on top of that, from what Steve had told him, Tony was quite protective of people he cared about, so he would also hate Bucky for trying to kill Steve and Natasha.

On receiving the text, Bucky sighed. He put the phone back in his pocket and looked down at Tony.

"Looks like our time's up, buddy." He pressed a kiss to Tony's forehead, and turned to head back to the tower. He helped get Tony comfortable in the now padded chair, wearing clothes that were ridiculously too big for him, and a pair of headphones to protect his ears. Tony started crying as soon as Bucky left him there, so Bucky stayed in the lab on the other side of the window, making faces at Tony to entertain him, until the light grew bright enough that it didn't matter anymore if he was there. Then he left, not wanting to see Tony. He pushed past the group gathered in the lab and headed down to the gym.

Bucky spent the entire night in the gym, and everyone else left him alone. He guessed that was Steve's doing, and sure enough, when the door opened early the next morning, it was Steve who greeted him.

"Hey Buck." He was aged up now. Bucky didn't turn to see him. He stayed where he was, pummelling a punching bag. "Tony upgraded the machine, spent all night on it. I figured you'd want to be alone last night, so I sent everyone who wasn't helping him to bed, told them not to bother you. Tony's staying in the lab for today, until they've re-aged everyone. So if you want to come up and get some rest, have something to eat, you're safe. Although I don't think Tony would really hate you that much, I think you're overreacting." Bucky hit the bag so hard it flew across the room and hit the wall, spilling sand over the floor. Bucky held his hand out and Mjolnir came zooming across the room, dropping his hand at the right moment sent the hammer flying after the bag, landing with a soft thump in the pile of sand. Steve raised an eyebrow. "Finally mastered the hammer then?" Bucky grunted in response. He still hadn't turned. Steve sighed. "Please come upstairs Buck. Or do I need to wrestle you to get you to eat and sleep?" Bucky turned slightly at this, looking at Steve and assessing the situation. He quickly came to the conclusion that Steve would win, easily, given the state he'd worked himself into. So Bucky submitted, allowing Steve to lead him upstairs, make him a quick breakfast, and guide him into bed. Throughout which Bucky didn't say a word.

Bucky's first thought when he woke that evening was for a shower. After he'd dressed, he decided to fetch a snack from the kitchen and then find Mack or Fitz and see if they could sort his arm out. It hadn't been in perfect condition when it was reattached, and working out for fourteen hours straight hadn't done it any favours. Now it was still functioning, but it was sticking slightly when he bent it in certain ways, and wouldn't move as far as it should when he tried to raise his arm. And he thought some of the water from his shower might have got inside which couldn't be good. But food was more important. So went to the kitchen and made himself a sandwich. He heard laughter from the next room, and headed through to investigate. What he found was all the Avengers and Coulson's team gathered on sofas in front of the TV, watching Natasha and Skye's videos. And Tony was there, sat next to Steve on one of the sofas. Bucky froze, unnoticed in the back of the room, sandwich in hand, no idea what to do.

Before he could make a decision, Tony glanced across and spotted him, face puzzlingly breaking into a big grin. "Hey, Bu-bu! Here, come sit with us," and he stood, offering Bucky his seat. Nonplussed, Bucky walked over and dropped into the seat, Tony perching himself on the arm next to him. Steve squeezed Bucky's knee, murmuring,

"Told you he wouldn't hate you." Bucky smiled weakly, and took a bite of his sandwich. He glanced nervously up at Tony, before thinking, _Screw it,_ and leaning his head against Tony's thigh. Tony began stroking his fingers through Bucky's hair as they watched three year old Clint throw a tantrum when baby Tony started playing with the blocks he'd abandoned hours ago, knocking down Clint's tower.

"It was a rubbish tower anyway," commented Tony. Clint snorted.

"Like you can do any better." Then he realised what he said, and added, "I mean at that age, obviously..."

"Yeah, I was gonna say. I mean my tower withstood an alien invasion, yours got taken down by a baby."

Coulson placed a hand on Clint's arm, hushing his protests before they began. Bucky glanced around at everyone, and spotted Thor sat on the floor by Steve's feet, hugging his hammer like a child with their favourite teddy bear. Bucky snorted at the sight. When asked, he simply pointed at Thor, who hugged the hammer tighter when attention was drawn to him.

The group stayed snuggled on the sofas, watching the videos, making jokes and laughing together, for hours, until they were interrupted by a call to arms.

"Looks like we aged you up just in time," Coulson said over the collective groaning as the Avengers prepared to leave. Clint threw a cushion at him. Bucky looked up at Tony, hopeful for a goodbye kiss, but instead Steve grabbed his arm and said,

"Come on, Buck, you're not gonna sit here while I go out and risk my neck are you?" Bucky was on his feet in an instant, rushing off to get ready with the rest of the Avengers.


End file.
